The host structure and the synchrotron radiation VUV-UV luminescence properties of samples BaMg2Si2O7 (BMSO):Ln (Ce3+, Eu2+) at different doping levels and different temperatures were investigated in detail. Three important aspects are studied to elucidate the luminescence properties of samples: (1) the vacuum referred binding energy (VRBE) scheme is constructed with the electron binding in the BMSO host bands and in the Ce3+ and Eu2+ impurity levels with the aim to explain the different thermal stabilities of Ce3+ and Eu2+ emissions; (2) the electron-vibrational interaction analysis on the narrow Eu2+ emission indicates a weak electron-phonon interaction in the current case; (3) by using three models (Inokuti-Hirayama, Yokota-Tanimoto, and Burshteǐn models) at different conditions, the energy transfer dynamics between Ce3+ and Eu2+ was analyzed. It reveals that the energy transfer from Ce3+ to Eu2+ via electric dipole-dipole (EDD) interaction is dominant while energy migration between Ce3+ is negligible. Finally, the X-ray excited luminescence spectra of samples BMSO:Ce3+/Eu2+ are collected to evaluate their possible scintillator applications.@en

Tuning of phosphor luminescence properties, including the emission energy/intensity and thermal stability, is an important way to develop superior luminescent materials for diverse applications. In this work, we discuss the effect of band gap engineering and energy transfer on the luminescence properties of Ce3+ or Pr3+ doped (Y,Gd)AGG systems, and analyze the underlying reasons for their different phenomena. By using VUV-UV excitation spectra and constructing VRBE schemes, the changes of host band structure, 5d excited level energies and emission thermal stability of Ce3+ and Pr3+ with the incorporation of Gd3+ ions were studied. In addition, the energy transfer dynamics was also investigated in terms of the luminescence decay curves. This work demonstrates a way to tune phosphor luminescence properties by combining band gap engineering and energy transfer tailoring and provides an inspiring discussion on the different results of Gd3+ doping on the Ce3+ and Pr3+ emissions.@en

Cationic tuning for lanthanide (Ce3+/Pr3+)-activated inorganic phosphors with stable, efficient, and fast-decay 5d-4f emissions has emerged as an important strategy toward the continuing pursuit of superior scintillators. The in-depth understanding of the cationic effects on photo- and radioluminescence of lanthanides Ce3+ and Pr3+ centers is requisite for the rational cationic tuning. Here, we perform a systematic study on the structure and photo- and X-ray radioluminescence properties of K3RE(PO4)2:Ce3+/Pr3+ (RE = La, Gd, and Y) phosphors to elucidate the underlying cationic effects on their 4f-5d luminescence. By using the Rietveld refinements, low-temperature synchrotron-radiation vacuum ultraviolet-ultraviolet spectra, vibronic coupling analyses, and vacuum-referred binding energy schemes, the origins of lattice parameter evolutions, 5d excitation energies, 5d emission energies, and Stokes shifts as well as good emission thermal stabilities of K3RE(PO4)2:Ce3+ systems are revealed. In addition, the correlations of Pr3+ luminescence to Ce3+ in the same sites are also discussed. Finally, the X-ray excited luminescence manifests that the K3Gd(PO4)2:1%Ce3+ sample possesses a light yield of ∼10,217 photons/MeV, indicating its potentiality toward X-ray detection application. These results deepen the understanding of cationic effects on Ce3+ and Pr3+ 4f-5d luminescence and inspire the inorganic scintillator development.@en

In this work, the crystal structure and electronic structure as well as the synchrotron radiation vacuum ultraviolet-ultraviolet-visible (VUV-UV-vis) luminescence properties of Li 6 Y(BO 3 ) 3 (LYBO):Ce 3+ phosphors were investigated in detail. The Rietveld refinement and DFT calculation reveal the P2 1 /c monoclinic crystal phase and the direct band gap of the LYBO compound, respectively. Only one kind of Ce 3+ 4f-5d transition is resolved in terms of the low temperature VUV-UV excitation, UV-vis emission spectra and luminescence decay curves. Furthermore, by constructing the vacuum referred binding energy (VRBE) scheme and applying the frequency-degenerate vibrational model, the impacts of 5d electron binding energy and electron-phonon coupling on luminescence of Ce 3+ in LYBO are analysed. The results show that the Ce 3+ emission in LYBO possesses a moderate intrinsic thermal stability. With the increase in concentration, the thermal stability of the emission gets worse due to the possible thermally-activated concentration quenching. In addition, the simulation of Ce 3+ emission profile at low temperature reveals that the 4f-5d electronic transitions of Ce 3+ ions can be treated to couple with one frequency-degenerate vibrational mode having the effective phonon energy of ∼257 cm −1 with the corresponding Huang-Rhys parameter of ∼6, which indicates a strong electron-phonon interaction of Ce 3+ luminescence in the Li 6 Y(BO 3 ) 3 host. Finally, the X-ray excited luminescence spectrum of the LYBO:5%Ce 3+ phosphor is measured to check the potential scintillator applications. @en

Luminescent materials with controllable colour evolution features are demanded for the development of multi-level anti-counterfeiting technologies. Here we report the structural and luminescence properties of CaMgSi2O6:Ln (Ln = Eu2+, Eu3+, Eu2+/3+) samples in detail and reveal their excitation-wavelength/temperature driven colour evolution characteristics. By tuning either the excitation-wavelength (276, 304, 343, 394 nm) or temperature (in the 330-505 K range), the designed samples with co-existing Eu2+/Eu3+ions can achieve diverse and controllable colour evolution from red, to pink, purple and blue. This shows their potential application in anti-counterfeiting with the help of sophisticated pattern design. In addition, the underlying mechanism of the Stokes shift of the Eu2+emission and valence stability of both Eu2+/Eu3+ions in CaMgSi2O6are also studied in depth. These results are valuable for designing colour-controllable luminescent materials based on the co-existence of the Eu2+/Eu3+ions for anti-counterfeiting applications.@en